SpaceAtlas Space Object Data
NASA JPL SBDB · 2018 HJ

2018 HJ

2018 HJ is an Amor-type near-Earth asteroid that approaches Earth from beyond our orbit without crossing it, orbiting the Sun at 2.168 AU once every 3.19 yr.

Amor Observations: 44
Orbital Period · P
3.19 yr
v(q)
34 km/s
v(Q)
12 km/s
Diameter · ≈
0.3 km
TJ
3.53
Eccentricity · e
0.4766

Orbit and dynamics

Between its closest point (1.135 AU) and its farthest (3.201 AU), the heliocentric distance changes by 2.066 AU over every revolution.

One full revolution takes 3.19 yr (1,166 days), computed from the semi-major axis of 2.168 AU.

The high eccentricity (0.477) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

The orbital plane is tilted 5.93° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 34 km/s at perihelion and falls to 12 km/s at aphelion.

Its perihelion lies just outside Earth's orbit, which is why it is classed as Earth-approaching rather than Earth-crossing.

Size and surface

No direct size measurement is available; from an absolute magnitude of H = 20.37 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.3 km.

Observation record and orbit quality

Astrometry from 44 individual observations underpins this orbit; the fit leaves an RMS residual of 0.4704 arcseconds.

Condition code U = 4 indicates a moderately constrained orbit; predictions decades ahead still carry noticeable uncertainty.

About these computed values

Orbital periods, perihelion and aphelion speeds, and diameter estimates on this page are computed by SpaceAtlas from the JPL SBDB orbital elements. They are derived quantities, not values copied from the source catalogue.

Orbital Parameters

Semi-Major Axis
2.168 AU
Eccentricity
0.4766
Perihelion
1.135 AU
Aphelion
3.201269 AU
Inclination
5.93°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
166.17°

Orbit diagram

The Sun sits at the focus (orange). Earth's orbit is the grey circle at 1 AU. The red dot marks the object's position at the catalog epoch.

3D orbit (interactive)

Drag to rotate; scroll or pinch to zoom. The Sun is at the focus (orange), Earth's orbit is the grey ring at 1 AU, and the red dot marks the object's current position.

Close approaches

Predicted close approaches to Earth, from NASA's Center for Near-Earth Object Studies (CNEOS).

Date (UTC)Miss distanceVelocity
2050-Jul-17 13:53 0.141957 AU
21236430 km
6.41 km/s

Distances in astronomical units (AU) and kilometres. Source: NASA/JPL CNEOS Close Approach Data API.

Physical Parameters

Diameter
— km
Albedo
—
Density
— g/cm³
Rotation Period
— h
Absolute Magnitude
20.37

Orbit Quality

RMS
0.47039
Condition
4
Orbit ID
—
Data source: NASA JPL Small-Body Database · NASA CNEOS. Orbital periods, perihelion and aphelion speeds, and diameter estimates on this page are computed by SpaceAtlas from the JPL SBDB orbital elements. They are derived quantities, not values copied from the source catalogue.

Keep exploring

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